Brachytherapy stent configurations

ABSTRACT

The invention describes method for delivering and positioning radio-isotopes. The method uses encapsulating free flowing medicament into a vehicle and positioning the vehicle into the body. Also provided is a system for delivering and positioning radio-isotopes into the body, the system comprising fluid radio-isotope encapsulated in a material.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to a system and method for delivering medicament,and more specifically this invention relates to radioisotope vehiclesand methods for configuring vehicles to optimize in vivo treatment.

2. Background of the Invention

There are a variety of ways to access and treat tissues in vivo. Often,one or a plurality of apertures near the treatment sight are made toallow access of surgical instruments, sutures, cauterizers, and thelike. Cannulas, associated trocars, wire guides, catheters are allvehicles to access the deep tissue treatment sites for the eventualsurgical or brachytherapy follow up.

The smaller the intervention physically, the more adaptable to multiplesituations. Attempts have been made to miniaturize instruments, stents,etc., to access narrow passageways (called lumens) such as ducts,arteries and veins, and generally hard to reach structures.

Brachytherapy usually involves the positioning of radioactive materials(packaged into discrete individual seeds) at tumor or vascular locationsso as to eradicate or shrink the tumors or positively affectrevascularization. Commercially available seeds generally have a centralcore of liquid or powder enclosed in a titanium shell or other rigidmaterial to filter out undesirable radiations. They are then batched byactivity.

Sometimes these tumor locations are accessed surgically near the surface(or exposed sites). Other times a large bore injection needle isrequired to position the radio isotopes into hard to reach areas such ashollowed out vertebrae, the esophagus, small diameter ducts and othersituations where direct surgical access is unavailable without causingcollateral damage from either external beam radiation or surgicalintervention. For example, needles are often relied upon to access theinteriors of vertebra for kyphoplasty treatment. Typical needles usedfor such injections are about 14 gauge diameters. This is because needlebore sizes having an inner diameter of approximately 1.6 mm) arerequired inasmuch as the smallest radio-isotope seeds have a crosssectional diameter of about 0.8 mm.

State of the art brachytherapy stents and devices are only slightlysmaller, with the limiting factor being the size of the radioisotopeseeds utilized for treatment. That the seeds have to be a certain sizeto provide an effective therapeutic dose combined with the fact thatseeds are typically not manufactured smaller than 0.8 mm in diametermeans that brachytherapy vehicles are too bulky to access small diameterlumens.

Brachytherapy, particularly with very low energy sources has theadvantage of minimizing collateral radiation but is very sensitive tooptimal seed placement. Either too high a dose or too low may haveunfortunate outcomes. Higher doses (e.g. delivered to the tissuesadjacent to the sources) have been necessary to deliver a cancerocidaldose to the tumor but this may lead to hemorrhage ulcerationfistulization, etc.

Strategies useful to decrease this gradient include the following:

-   -   increasing the number of radioactive seeds;    -   filtration of the radiation emanating from the closest sources;    -   padding (i.e., increases the distance between radiation sources        and sensitive tissues);    -   increasing the radioactive source energy but while also        minimizing exposure of healthy tissues; and    -   increasing the distance between radiation sources and sensitive        tissues.

Additionally, radiation oncologists are most comfortable if anhomogenous radiation dose distribution is achieved.

A need exists in the art for a system and method for treating deepseated neoplasms. The system and method should be capable of deliveringmedicaments through small pores. Also, the system and method couldincorporate shielding to prevent in situ over exposure of tissue toradiation.

SUMMARY OF INVENTION

An object of the invention is to provide a system and method forconducting brachytherapy that overcomes many of the drawbacks of theprior art.

Another object of the invention is to provide a system and method forpositioning medicament in deep seated tissue sites. A feature of theinvention is utilization of fluid-phase medicament encapsulated inreversibly deformable material. An advantage of the invention is thatthe size, such as the cross diameter, of the deformable vehicle could beminimized. Another advantage is that the vehicle replaces the shieldinginherent in solid radioactive seeds.

Still another object of the invention is to provide a system and methodfor enabling in vivo positioning of radioisotopes in brachytherapy. Afeature of the invention is encapsulating free flowing liquid-phaseradioisotopes within a solid phase vehicle having semi-radio-opaquecharacteristics. An advantage of the invention is that the vehicle maybe reversibly inserted into heretofore inaccessible tissue sites, suchas very narrow ducts, collapsed vertebrae, cavities, surgical sites, andother lumens. Another advantage is that liquid isotopes makes smallerpreloaded catheter ribbons, rectangles, triangles, semicircular, andother shaped delivery vehicles feasible.

Briefly, the invention provides a method for delivering and positioningradio-isotopes into the body, the method comprising encapsulating freeflowing radio-isotope into a vehicle; and positioning the vehicle intothe body.

Also provided is a system for delivering and positioning radio-isotopesinto the body, the system comprising fluid radio-isotope encapsulated ina material.

BRIEF DESCRIPTION OF DRAWINGS

The invention together with the above and other objects and advantageswill be best understood from the following detailed description of thepreferred embodiment of the invention shown in the accompanyingdrawings, wherein:

FIG. 1A is a schematic elevational view of a brachytherapy stent/sleevestent configuration, in accordance with features of the presentinvention;

FIG. 1B is a schematic prospective view of a spiral vehicle, inaccordance with features of the present invention;

FIG. 1C is a schematic depiction of an orthopedic medicament deliverydevice, in accordance with features of the present invention;

FIG. 2 is an elevational view of a vertebral column with an accessaperture;

FIG. 3A is perspective view of a plurality of concentrically arrangedundeployed brachytherapy vehicles prior to insertion into a vertebralcolumn, in accordance with features of the present invention;

FIG. 3B is a perspective view of deployed brachytherapy vehicles, inaccordance with features of the present invention;

FIG. 4A is a perspective view of an array of brachytherapy vehicles inparallel relation to each other, in accordance with features of thepresent invention;

FIG. 4B is a perspective view of a single brachytherapy vehicle shapedas a ribbon, in accordance with features of the present invention;

FIG. 5A shows an undeployed bifurcated medicament vehicle, in accordancewith features of the present invention;

FIG. 5B shows a bifurcated medicament vehicle deployed over a guidewire, in accordance with features of the present invention; and

FIG. 6A depicts an after-loaded catheter defining a semi-circular crosssection, in accordance with features of the present invention;

FIG. 6B depicts an after-loaded catheter defining a cut our or notch toform a U-shaped cross section, in accordance with features of thepresent invention;

FIG. 6C depicts an after-loaded catheter defining a square crosssection, in accordance with features of the present invention; and

FIG. 6D depicts an after-loaded catheter defining an ovoid-shaped crosssection, in accordance with features of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description ofcertain embodiments of the present invention, will be better understoodwhen read in conjunction with the appended drawings.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (e.g., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and5).

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

As used herein, an element or step recited in the singular and precededwith the word “a” or “an” should be understood as not excluding pluralsaid elements or steps, unless such exclusion is explicitly stated. Asused in this specification and the appended claims, the term “or” isgenerally employed in its sense including “and/or” unless the contentclearly dictates otherwise.

Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. Moreover, unlessexplicitly stated to the contrary, embodiments “comprising” or “having”an element or a plurality of elements having a particular property mayinclude additional such elements not having that property.

The invention provides a method and system for inserting andrepositioning medicaments in hard to reach spaces within the body. Asalient feature of the invention is that the medicaments are fluidized.This allows for replacement of solid phase seeds which leads tominiaturization and manipulation of the physical vehicles containing themedicaments. For example, if one seed occupied a 1 mm, 10 mm long tube,the estimated radioactive source would be about 1 to 4 mm cubed whereasif the entire tube was filled with radioactive sources as in a liquid;the radioactivity would occupy 31 mm cubed in volume. The volume wouldbe greater if multiple tubes are welded or otherwise gathered together(e.g., to form a ribbon) in a custom fit to a particular tumor-excisionsite or treatment site.

Generally, the vehicles are hollow wires having various cross sectionsadapted to receive fluidized medicaments. To accommodate the treatmentof tiny lumens such as ducts, medicament delivery vehicle cross sectionsof between 1 mm and 10 mm are suitable.

Given the small diameter of the wires, medicament may be loaded thereinvia capillary action. Then, over time, medicament such aschemotherapeutic agents, antibiotic or other topically-operable drugsmay exit either pores or both ends of the wire, via osmosis or surfacetension created by contact between the ends and adjacent mucosa.

However, in the case of brachytherapy, after wire loading, the ends ofthe wire may be sealed so as to prevent direct exposure of radioisotopeto body tissue. Further, the vehicle may be selected to confer partialradioactive shielding. For example, nitinol wire shaped memory polymersor other materials, may be used to prevent over exposure or thedevelopment of hot spots at treatment sites.

The wire vehicle may define be a continuous, unbroken cavity into whichis deposited the chosen medicament. As such, the wire vehicle has afirst end and a second end. One such vehicle is that depicted in FIGS.1B, 1C, 3A, 3B, and 4, discussed below.

Alternatively, the wire vehicle may be discontinuous along its lengthsuch that it has a first end, a second end, a first intermediate end anda second intermediate opposing the first intermediate end. Such a deviceis depicted in FIG. 1A. A sleeve may overlay the first and secondintermediate ends and in slidable communication therewith. This allowsfor the wire to be extended at its first and second ends while stillconferring radioactive shielding to mucosa proximal to the sleeve, andperhaps in physical contact with the sleeve.

FIG. 1A depicts a basic component of the invented system, generallydesignated as numeral 10. FIG. 1 depicts a tubular shaped vehicle 12partially encircled by a sleeve 20. A first end 14 and second end 16 ofthe vehicle protrudes from opposite ends of the sleeve. Intermediateends 18 of the vehicle oppose each other and are overlaid by the sleeve20. The sleeve may be in slidable communication with the vehicle. Thissliding feature allows the spiral, originally overlaid by the sleeve, tobe uncovered so as to expand in diameter. The sleeve provides additionalshielding from over exposure to radiation contained in the alreadyattenuating vehicles.

The construct depicted in FIG. 1A is shown partially deployed. However,when the construct is manipulated so that more of the vehicles arenested within the sleeve, the sleeve will serve as additionalattenuating substrate to prevent over radiation from the vehicles 12crowded within the sleeve. Alternatively, the sleeve 20 may be fixed toportions of the vehicle 12 to prevent sliding and confer permanentcoverage/shielding to that region of the vehicle. This permanentshielding will prevent medicament overexposure of mucosa 22 situatedproximal to the sleeve 20. When spiral vehicles are used, the sleeves 20allow increasing spiral radial diameter in portions of the devicewithout necessarily increasing or decreasing the length of the spiral orthe construct.

The vehicle is filled with free flowing medicament, such aschemo-therapy fluids, fluid radio-isotopes, etc. As discussed supra, ifthe vehicle is filled with radio-isotopes, the vehicle should behermetically sealed to prevent leakage. An advantage of liquid filledvehicles is that the spiral dimensions of the vehicle may be tighter soas to pass through smaller lumens.

FIG. 1A depicts the vehicle 12 as a tube with a circular cross section.However, the vehicle may also define an oval cross section, a squarecross section, a triangular cross section, a rectangular cross sectionor some other polygonal shape.

The delivery mechanism may further comprise a plurality of vehiclespositioned relative to each other to mimic the shape of its restingplace (e.g., the tumor excise cavity) within the body. For example aplurality of tubes may be gathered together to form a flat substrate.This would be particularly effective if the cross section of the tubeswere actually rectangular or square as opposed to circular, so as toallow dense packing of the tubes against each other to form a sheet.

Spiral Detail

FIG. 1B shows a spiral shaped vehicle 13 for encapsulating fluidizedmedicaments such as liquid or gaseous radio-isotopes or a liquid-gasmixture. A gap “g′” extending parallel to the longitudinal axis of thespiral and defined by adjacent hoops of the spiral provides a means formaintaining flowage of liquids through the lumen, such as a duct.Depending on the type of material forming the spirals, memory shapematerial may cause larger gaps to form in vivo when the vehicle issubjected to body temperatures. Spirals defining smaller gaps or spiralsabsent any gaps may be utilized when lumen impairment is less of aconcern or problem. Spirals may have varying radial diameters atmultiple locations along its length to accommodate varying targetshapes.

The longitudinal gap ‘“g” will vary depending on many circumstances andsituations. Generally, gap distances may vary from 0 mm to 10 mm.

FIG. 1C depicts a spiral shaped vehicle 13 encircling the periphery of abone support rod 15 or other structure. The vehicle 13 may be fully orpartially embedded into the surface of the rod. In such partialembedment, the vehicle is countersunk relative to the surface of the rodand reversibly adhered thereto so as to be removed, replenished, orreplaced. For example, the ribbon or other device fits in a groove onthe surgical rod. The rod may further be encircled by the sleeve 20depicted in FIG. 1A.

The iteration depicted in FIG. 1C also provides a means to decreaseexternal beam radiation. Usually when an orthopedic device e.g. rod isplaced across a pathologic fracture in a long bone the entire bone andmuch soft tissue is included in the volume. The metal rod also partiallyshields the cancerous tissues. Also, the integral radiation dose ishigh. By wrapping or otherwise incorporating radioisotopes with the rod,less radiation is necessary to treat the same tissue. Furthermore, ifclinically indicated, additional devices (e.g., external beam boost,etc.) could be added to ensure adequate treatment of the canceroustissues.

FIG. 2 depicts a vertebral column as a potential treatment venue for aplurality of medicament delivery vehicles illustrated in FIG. 3A-B. Eachvehicle 24 defines a triangular shaped cross section, arranged to form acircle. The center of the circle further comprises a balloon 26 or othermeans for biasing each of the vehicles to the periphery of the circlewhen the balloon is inflated or the means is actuated.

Commercially available balloons, such as those used for orthopaedicapplications are suitable for this aspect of the invention. For example,Kyphon™ brand balloons (Medtronic Spinal and Biologics, Inc, Memphis,Tenn.) are inflatable bone tamps (IBT) that have maximum rated inflationpressures of e.g., 700 psi when used with its inflation syringe. Suchfeatures are preferred in kyphoplasty applications discussed supra. Amyriad of balloon sizes and volumes are available (e.g., 10 mm/3 cc, 15mm/4 cc and 20 mm/5 cc) and in access profiles of about 10 gauge. Othermeans may include a permeable saline bag that inflates due to osmosis.Preferably, these medicament vehicle actuation means are biocompatible.

In this treatment scenario, an access opening 30 to a collapsedvertebrae 28 is provided. The medicament delivery construct 23 isinjected or otherwise placed within the vertebrae in its deflated orundeployed configuration FIG. 3A. The construct is shown as a pluralityof vehicles, each vehicle sized in similar, straight lengths dependingon the treatment site and cavity. For example, in kyphoplastyapplications, the vehicles may each be about e.g., two cm in length.Spirals may also be used in combination with the straight lengths, or inreplacing the straight lengths.

Once positioned inside of the vertebrae 28, the balloon 26 is actuatedand the individual vehicles are biased in a radial direction (FIG. 3B)until they contact the interior surfaces of the hollowed-out vertebrae.In this iteration, the shaped devices fill the iatrogenically producedvolume. As such, the radio-isotope filled vehicle defines a netting orframework of sorts lining the interior of the periphery. Fluid underpressure may be injected into the balloon to expand the vertebra and thespace filled with cementum. In one scenario, the cementum resides withinthe void such that the medicament filled vehicle is positioned betweenthe cementum filled void and the interior surfaces of the vertebrae.

Ribbon Detail

The wires may be combined to form structures such as ribbons. In suchinstances, the eventual flexible planar structures, for example may beabout 5 mm wide and about 1 mm in height or thickness. This will rendera medicament reservoir or volume of about 50 mm³.

Specifically, wires with a circular or non-circular cross section may bearranged side by side to form a plane or ribbon. Alternatively, a singlevehicle with a single, continuous, uninterrupted or un-partitionedcavity may be employed as depicted in FIG. 4B.

Longitudinally extending gaps between the individual ribbons may or maynot exist in vivo. Alternatively the wires and or ribbons may bepositioned next to each other such that no gaps exist when the constructis positioned in the body, but gaps later form due to the body heatingup the memory shaped substrate. This formation of gaps is multi-fold inpurpose, including expanding stent shape to the boundaries of any tumorexcision cavity to confer maximum treatment of adjacent tissue.

A pattern of hollow ribbons can cover a tiny structure with a smallimpingement on the lumen. In certain situations such as such ascholangial pancreatic ducts any narrowing can lead to sludging,congestion, or partial obstruction. Coating of the interior wall maydecrease this risk. Some stent devices can be placed via duodenalretrographic approach, ERCP retroduodenography, or extra hepaticpercutaneous placement. A biocompatible adhesive may be placed on theexterior of the device to adhere to the adjacent tissue, therebyreducing risk of slippage with the adjacent tissue.

FIG. 4A is a perspective view of a medicament delivery system 40comprising a plurality of conduits 12 arranged in parallel. The finalconfiguration of this delivery system is ribbon-like, so as to bereversibly flexible. To maintain the ribbon or flat configuration, aframe 42 or adhesive is applied to the top, bottom or peripheralsurfaces “s” of the ribbon. Alternatively or in addition, the conduitsmay be fixed in place relative to each other by welding, adhesive wrap44, such as film comprising polyvinyl chloride (PVC), polyethylene (PE),polyolefin (POF), and combinations thereof. The wrap may completelyencircle the ribbon. An alternative is to have a hollow ribbon defininga single continuous unbroken void, e.g., an inner cross section withdimensions of 5 mm by 1 mm. It is envisioned that the entire device havea memory shape.

FIG. 4A depicts the conduits have a circular cross section but othergeometric shapes are also suitable, as discussed supra. Further theconduits may each define a spiral.

Also, while FIG. 4A depicts straight conduits in parallel with eachother, the entire ribbon may be contorted such that the conduits are notstraight but perhaps define a curve, a spiral as mentioned above, or asine wave configuration. Furthermore, tubes forming the longitudinalperiphery of the ribbon may be peeled away from the frame 42 or adhesiveif the surgeon requires a more narrow stent. These features allow thedevice to be conformed to whatever duct or excise site is being treated.

FIG. 4B shows a single void space ribbon iteration, the void space isdefined by a single vehicle having cross section with a height at afraction of its width. For example, the a cross section measurement of0.5-1 mm high “h” by 3-6 mm in width “w” is suitable.

Ribbon-like vehicles confer advantages over prior art designs. Forexample, ribbons decrease tubular skin distortions inasmuch as theribbons have a relatively thinner profile. Depending on the materialused (e.g., nitinol) comprising the individual medicament vehicles, thefinal forms may have a memory shape. This will allow the surgeon toplace the vehicle into the excision space with the anticipation thatovertime, the vehicle may revert to its more compacted or expandedconfiguration as a consequence of its contact with mucosa defining theperiphery of the excision space.

Bifurcated and trifurcated devices maybe used when the tracheal carina,bronchial bifurcations and other sites such as hepatic duct bifurcations(Klatskin's tumor) are treated. FIG. 5 is an example of a bifurcatedvehicle 46. FIG. 5A shows a pre-deployed vehicle. FIG. 5B shows abifurcated vehicle conforming to guidewires 48. The bifurcated ortrifurcated device may feature a distal taper.

The bifurcation/trifurcation is meant to irradiate a tumor orvasculature (including arterio venous shunts) that crosses anatomicalbifurcations to deliver a uniform radiation dose avoidingoverlap/underlap situations. This may also decrease the likelihood ofdislodgement by e.g. coughing retching etc. As such, it is a doublewalled device defining an annular space 47 adapted to receivemedicament, for example fluidized radioisotope. As with other vehiclesdescribed herein, the open ends of the annular spaces may be sealed withbiocompatible adhesive, wax, solder, heat or UV welding, crimping, orother means. Generally, when working with radioisotopes having longhalf-lives, these sealing means should withstand the physiologic andchemical environments of the body so as to assure the isotopes remainsequestered within the walls of the vehicle.

The device could be a solid tube or a spiral. In these situations, thedevice may be passed through an endoscope or possibly via guidewires orother means. The guidewires may be passed through each bronchus and thepreformed device slid over the wire, possibly under the scrutiny offluoroscopy. Once the device is in place, the guide wire may be removed.

Medicament and Loading Detail

Loading of the afore-described conduits is straight forward, and mayinclude the use of capillary action, pressure injection, or simpleimmersion of the vehicles in the selected liquid medicament for a timeto cause the medicament to migrate to all regions of the conduit. Thethen loaded delivery system is inserted into the treatment or tumorexcise site. The benefit of the ribbon configuration depicted in FIG. 4is that the ribbon may allow for a thinner stent wall, a smoother stent,larger internal volume, and therefore less interruption of the passageof bodily fluids.

The incorporation of liquid medicaments allows multiple vehicle shapes,even irregular asymmetrical ones. This allows the physician to fill indefects. Also, preloaded vehicles allows the surgeon to be shaped insurgery by the physician.

Another advantage of using fluid radio-isotopes is the dissemination ofthe radiation sources adjacent to or within a delivery conduit. Thisessentially decreases the dose gradient within the conduit. Furthermore,if the delivery conduit comprises nitinol metal, that metal will filterundesirable lower energy radiations, to further minimize over exposureof healthy tissue. Typical therapeutic dosage energies range from 20 kevto about 100 kev. Lower energies (e.g., 20 to 60 kev) allow the patientto be in public with relatively simple shielding. Higher energies (e.g.,above 70 kev) require the patient to wear special shielding to protectothers. Radiation is delivered over weeks or months to a year in the lowdose rate treatment scenarios. This effect is biologically differentwhen radiation is delivered over a very short period of time.

Also, fluid isotopes, such as liquid isotopes allows increasedflexibility as to the selection of delivery canisters, including the useof spiral configurations smaller than possible when prior art solidradio-isotope seeds were used. Embodiments of the spiral may includeloosely wound spirals or tightly wound spirals. Loosely wound spiralsdefine gaps between the spiral loops. This allows for less impairment orblockage of the physiological lumen, so as to allow continuedphysiological function. Tightly wound spirals define very small or nogaps between their loops and may be used when lumen impairment is not anissue. These smaller configurations allow treatment of similarly smallertubular luminal structures, and without gaps between coplanar ribbons,if so desired. As such, the ribbons may be positioned side by side toprovide a continuous surface emanating therapeutic radiation.

Physiologic luminal structures envisioned for treatment with theinvented system include those of the esophageal, colon, gastric,bronchial, biliary, pancreatic, and vascular structures.

The usually preloaded catheters as described above may be inserted intoafter-loading catheters of the types depicted in FIGS. 6A-D.Semi-circular after loading catheters 52 (FIG. 6A) and notchedsemi-circular after loading catheters 54 (FIG. 6B) are suitable,particularly in efforts to minimize or eliminate the creation of hotspots on mucosa and other healthy tissue. With the semi-circular afterloading catheter, a wire 12 full of liquid medicament is slidablyreceived by the catheter, thereby “loading” the catheter. The volumeincluded by the shaped, after loaded catheters could then be expanded(by inflating a balloon centrally located within the after loadedcatheter) to fill the desired space. A notch 60 may be provided todecrease any potential hotspot at that location of the after-loadingcatheter.

After-loading catheters with a square shaped cross section 56 (FIG. 6C)may be suitable, wherein a portion of the interior of the catheter isfilled with radiation attenuation material 57. Similarly, an ovoidafter-loading catheter (FIG. 6D) may contain a mass of attenuationmaterial 57. The attenuation material may be adhered to onelongitudinally extending interior surface of the after-loading cathetervia adhesive, heat weld, chemical weld, or similar means. Alternatively,the attenuation material may be integrally molded with the after-loadingcatheter. Medicament filled wires 12 or ribbons slidably interact withthese catheters, thereby nesting within the after-loaded catheters.

It will be appreciated that the conduits need not be fully loaded withfluid medicament. Rather, the conduits 12 may be partially filled, asdepicted in FIG. 6A, so that between 10 and 80 percent of the conduitsare full of fluid medicaments. This may result in the establishment of ahead space above the fluid. In the case of fluid radio-isotopes, partialfilling will aid in attenuating dosage and therefore minimize theformation of hot spots proximal to the head space that would otherwiseform on mucosa lining the treatment site.

In another iteration, plastic tubing can have a nitinol ribbon dictatingthe shape.

In the case of brachytherapy, a myriad of radio-isotopes are availableas fluidized means for radioactivity. Suitable isotopes are those thatare in fluid phase with Kev ranges of between approximately 20 Kev toabout 600 Kev, and preferably between 20 Kev and 110 Kev. For example,radio-isotopes selected from the group consisting of Iridium 192, Iodine125, Cesium 131, Samarium 153, Palladium 103, and combinations thereofare suitable. Other isotopes having similar key ranges may be used whenthey become available.

In operation, any of the aforementioned configurations are first loadedwith medicament. Then, the configurations are form fitted to thetreatment site and either surgically implanted in the site or injectedthere via a syringe or interventional radiology devices. (Interventionalradiology uses image-guided technology such as X-rays, fluoroscopic CTscans, and MRI to perform minimally invasive procedures.)

The vehicles may be later harvested once dosage is delivered, or elseleft in the body for possible passage, eventual decomposition viaphysiologic means such as plasma pH levels, microphage action, or justleft in situ.

The vehicles may be utilized singly or as a plurality. While the sizesof the vehicles will depend on their ultimate use, the inventorenvisions vehicle lengths ranging from 5 mm to 100 mm, and vehicle crosssection diameters ranging from 0.5 mm to 50 mm.

In summary, the invention provides a method for delivering andpositioning medicaments into the body, the method comprisingencapsulating free flowing radio-isotope into a vehicle and positioningthe vehicle into the body. The vehicle may comprise radioactiveshielding material. A salient feature of the method is that themedicament is a fluid, and particularly a liquid.

The vehicle sequestering the medicament is a semi rigid materialselected from the group consisting of metals such as nitinol, platinum,stainless steel, tungsten, their various alloys, memory shapedsubstrates, coated polymers, and combinations thereof. The vehicle maycomprise a plurality of tubes wherein the tubes are parallel with eachother. The tubes have a first end and a second end and the tubes eachhave a cross section with a geometric shape selected from the groupconsisting of a circle, a square, a triangle, a rectangle, an oval, andcombinations thereof. (Nitinol-comprising vehicles with these crosssections are commercially available, for example from Fort Wayne Metals,Fort Wayne, Ind.) Furthermore, the vehicles may be moved relative toeach other after the vehicles are placed in the body. The step ofpositioning the vehicle in the body comprises interventionalradiographic means or injecting the vehicle into the body with asyringe.

The invention also provides a system for delivering and positioningradio-isotopes into the body, the system comprising free flowing fluidradio-isotope encapsulated in an elongated substrate. The step ofpositioning the ribbon in the body comprises inserting the ribbon intothe body via a vehicle selected from the group consisting of syringe,needles, trocars, endoscopic instruments, interventional radiologytechniques, and combinations thereof. The substrate may besemi-radio-opaque. In embodiments of the system, the substrate is aplurality of conduits, each conduit defining a cross section shapeselected from the group consisting of a circle, a square, a triangle, arectangle, and combinations thereof. Each of the conduits may be movablein situ relative to each other.

The substrate may be shaped as a spiral (or a tube or other shapes)having a first end and a second end, a first intermediate end and asecond intermediate end, whereby the first and second intermediate endsoppose each other. The first and second intermediate ends may beoverlaid by a sleeve. The sleeve may slidably communicate with thespiral. The sleeve may be radio-opaque. The first and secondintermediate ends may be overlaid by the sleeve.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from its scope. While the dimensions and types ofmaterials described herein are intended to define the parameters of theinvention, they are by no means limiting, but are instead exemplaryembodiments. Many other embodiments will be apparent to those of skillin the art upon reviewing the above description. The scope of theinvention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the terms“comprising” and “wherein.” Moreover, in the following claims, the terms“first,” “second,” and “third,” are used merely as labels, and are notintended to impose numerical requirements on their objects. Further, thelimitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. § 112, sixth paragraph, unless and until such claimlimitations expressly use the phrase “means for” followed by a statementof function void of further structure.

As will be understood by one skilled in the art, for any and allpurposes, particularly in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” “more than”and the like include the number recited and refer to ranges which can besubsequently broken down into subranges as discussed above. In the samemanner, all ratios disclosed herein also include all subratios fallingwithin the broader ratio.

One skilled in the art will also readily recognize that where membersare grouped together in a common manner, such as in a Markush group, thepresent invention encompasses not only the entire group listed as awhole, but each member of the group individually and all possiblesubgroups of the main group. Accordingly, for all purposes, the presentinvention encompasses not only the main group, but also the main groupabsent one or more of the group members. The present invention alsoenvisages the explicit exclusion of one or more of any of the groupmembers in the claimed invention.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:
 1. A method for deliveringand positioning radio-isotopes into a body, the method comprising: a.encapsulating a free flowing fluid-phase radio-isotope into a singlecavity hollow ribbon that is unpartitioned to establish a continuous andhomogeneous radiation dose distribution, wherein the ribbon comprisesmaterial to minimize radiation over-exposure of healthy tissue; and b.positioning the ribbon into a lumen of the body.
 2. The method asrecited in claim 1 wherein the ribbon comprises radioactive shieldingmaterial selected from the group consisting of nitinol, platinum,stainless steel, tungsten, coated polymers, memory shaped substrates,and combinations thereof.
 3. The method as recited in claim 1 whereinthe radio-isotope is a gas.
 4. The method as recited in claim 1 whereinthe radio-isotope is a liquid.
 5. The method as recited in claim 1wherein the radio-isotope is a mixture of liquid isotopes and gaseousisotopes.
 6. The method as recited in claim 1 wherein the ribbon is asemi rigid material selected from the group consisting of nitinol,memory shaped polymer, alloy, and combinations thereof.
 7. The method asrecited in claim 1 wherein the ribbon comprises a plurality of tubeswherein the tubes are parallel with each other.
 8. The method as recitedin claim 7 wherein the tubes have a first end and a second end and eachof said tubes has a cross section with a geometric shape selected fromthe group consisting of a circle, a square, a triangle, a rectangle, anoval, and combinations thereof.
 9. The method as recited in claim 7wherein the tubes are moved relative to each other after the ribbon isplaced in the body.
 10. The method as recited in claim 1 wherein thestep of positioning the single cavity hollow ribbon in the bodycomprises inserting the ribbon into the body via a vehicle selected fromthe group consisting of: a syringe, needles, trocars, endoscopicinstruments, interventional radiology techniques, and combinationsthereof.
 11. The method as recited in claim 1 wherein the material is asemi rigid material selected from the group consisting of nitinol,platinum, stainless steel, tungsten, their various alloys, memory shapedsubstrates, coated polymers, and combinations thereof.